Stepping mechanism



Deu. 27, 1927. 1,653,888

M. P. CHAPLIN STEPPING MECHANISM Filed March 15, 1924 Patented Dec. v27, 1927.

UNITED STATES PATENT OFFICE.

MERLE PEABODY CHAIiIN, OF WHITE PLAINS, NEW YORK, AS'SIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION Ol' NEW YORK.

Application led March 15,

This invention relates `to an actuating mechanism employing a pawl and ratchet wheel for eiiectin the step-by-step movement of the switc operating element of a selector used in automatic telephone systems, and more particularly it relates to a. self-interrupting stepping magnet for advancing a switch on the back stroke of the magnet amature.

The object of this invention is to improve the etliciency and reduce the maintenance cost of such devices.

There are a number of stepping devices known in which the work is done on the back stroke of the armature of the stepping magnet; that is to say, the magnet when energized stores up mechanical energy in a spring which on the opening of the circuit of the magnet does the work of advancing the shaft while the armature is recovering its stroke. In these self-interrupting magnet structures an adjustable. make and break Contact device is provided to control the energization and deenergi'zation ofthe magnet at the proper time. vThis contact device is adjusted to provide a long closure of the contacts to permit the magnet to build up itseld to the proper strength and before the end of the stroke is reached this contact must be opened to prepare for the back stroke, but at this instant the pawl has not yet reached the next tooth 1n the ratchet wheel and so the momentum of the moving parts must be used to throw the armature the remaining distance to permit the pawl to engage said tooth. However, as soon as the magnet circuit is opened, the retracting spring of the armature comes into play and opposes this further throw, vand inasmuch as' the moving parts are light and have little inertia, the amount of armature travel after the magnet current is cut oi is rather small. Conversely, since the contact closes again early in the back or driving stroke of the armature, the circuit is closed through the magnet and it begins to build up vin opposition to the retracting s ring. This means that the springmust e so constructed that it works faster than the magnet can build up its operating strength. This is particularly objectionable when the stepping magnet has to drive a variable load wherein the amount of friction varies with the number of contacts passed over by the STEPPING MECHANISM.

1924. Serial No. 899,462.

switch brushes, thus varying the rload. It is I8 therefore evident that in devices of this type there is very little margin of adjustment between the point where the current can be cut oi'i on the motive stroke, and have the armature complete its motion against the 00 retractile spring, and the point on the driving stroke Where the current may be reapplied without preventing the armature from completing its back or driving stroke. Adjusting the contact so as to energize the 06 electromagnet longer on the motive stroke means that the current will be reappliedf to the electromagnet earlier on the driving stroke and 'conversely adjusting the contact to provide an earlier cut-off on the motive stroke will provide a later reapplication of energy to the magnet on the drivin stroke.

In the stepping devices heretol ore used, considerable diiiculty has also been encountered due to excessive and unequal wearing away of the bearings and the resulting loss in etliciency. This has been caused chiefly by the torque or twisting action at the bearings produced b the moving members.

In accordance wit this invention means is provided for determining the point at which the circuit through the electromagnet will be opened during the motive stroke and additional means is likewise provided for determining the point at which the circuit g5 through the electromagnet will be closed again during the driving stroke. As the means for opening the circuit is independent from the means for closing the circuit again, the opening of the circuit may be advanced or retarded without aecting the closing of the circuit. Likewise the closing of the circuit may be advanced or retarded without aii'ecting the opening of the circuit.

A feature of 'this invention is the eliminaon tion of torque on the bearings of the various moving members anda consequent gain in eiiiciency.

Another feature of the invention is the adjusting arrangement for the main armature. 10o Another feature of this invention is the arrangement for regulating the tension of the retractile spring and locking the bearing shaft of the ratchet or driven member.

Referring to the drawing, which comprises m5 but a single sheet, Fig. 1 is a diagrammatic representation of the stepping mechanism in its normal position; Fig. 2 is a similar reprethe spring tension regulator;

sentation of the same device at the end of the motive or operating stroke of the main armature; Fig. 3 is a front view of either Fig. 1 or Fig. 2; Fig. 4 is a detail view of Fig. 5 is a detail view of the ratchet bearing; Fig. 6 is an alternative form of magnet structure.

The electromagnet (orV motor magnet) 1 is furnished with a main armature 2, pivoted at 3. The limits of travel of the armature 2 are regulated by the set screws 4 and 5. An extension piece of the main armature 2 terminates in a lug 7. A yielding spring member 8 is secured at 27 to the main armature 2. An auxiliary armature 9 is secured at 23 to a thin magnetic reed or pivot 24 which is secured at 12 to the pole piece 11 of the electromagnet 1. The pawl 17, which drives the ratchet 18, is secured at 22 to an extension of the main armature 2. The retractile spring 21 is tensioned when the main armature 2 is operated (on the motive stroke of the stepping mechanism, Fig. 2). The contact springs 14 and 15 are so tension that they tend to separate from each other, the contact spring 14 pressing the insulated spacing eleme'nt 13 against the auxiliary armature 9 in a direction tending to force the auxiliary armature away from the pole piece 10.

The principle of operation is as follows:

When the stepping mechanism is in its normal position the retractile spring 21 tensions the extension piece 6 of the main armature 2 so as to cause the spring member 8 to make physical contact with the auxiliary armature 9, and hold it in position against the face of the pole piece 10. In this condition the contact spring 14, to which is rigidly secured the spacer 13 so that the spring 14 and pacer 13 move in unison, is in firm contact with the spring 15. When the key 16 is closed (as shown in Fig. 2) the electromagnet 1 is energized and the main armature 2 is operated, moving from the normal position Fig. 1 to itsoperated position Fig. 2. The force of attraction exerted by the electromagnet 1 upon the auxiliary armature 9 is sufcient to overcome the opposition of the tensioned spring .contact 14 so as to retain the auxiliary armature 9 in close physical contact with the pole piece 10 after the spring member 8 moves away from the auxf iliary armature 9. Hence, the contact springs 14 and 15 will remain closed. Towards the end of the motive stroke of the main armature 2, the lug 7 presses against the auxiliary armature 9 and after overcoming the mgnetic field through the auxiliary armature 9 and pole iliary armature away from the pole piece, causmg the contact springs 14 and 15 to separate (as shown in Fig. 2) opening the electrical circuit through the electromagnet 1.

piece 10, forces the aux It in evident that since the contact spring 14 is always seeking to release the auxiliary armature 9, the force which the lug 7 coutrolled by the main armature 2 will be required to exert will be very small. The contact spring 14 by means of the insulated s spacer 13 now forces auxiliary armature 9 against the back stop 25. At the same time the pawl 17 which moves in unison with the main armature 2 is stepped out of engagement with the tooth 19 and into position to engage the tooth 20 of the ratchet 18. It should be understoodthat to force the auxiliary armature 9 away from the pole piece 10, the lug 7 and consequently the main.armature 2 is only required to travel a `relatively short distance and that the auxiliary armature 9l thereafter moves a greater distance causing a relatively large separation between the contact springs 14 and 15.

The retractile spring 21 now functions to return the main armature 2 to its normal position or to initiate the driving stroke of the stepping mechanism. During the driving stroke (preferably when the armature is in the middle of its return movement) the spring member 8, overcoming the opposing tension ot' the contact spring 14. forces the auxiliary armature 9 against the pole piece 10, whereupon the contact springs 14 and 15 are again closed and the cycle of operations is repeated. Although the contact springs 14 and 15 are closed causing the electromagn-et to commence building up its field when the return of the main armature 2 is only approximately half completed, the main armature 2 continues and completes its lreturn movement because the electromagnct does not build up quickly enough to prevent it from so doing. The closing of the circuit ot' the electromagnct .during the return movement of the main armature. 2 tends to speed up the operation of the switch to advance the time of. the commencement of the reenergization of the electromagnet. Advancing the time of the connnencement of the rcenergization of the electromagnet also results in a cushioning or shock absorbing effect being produced upon the main armature 2 Whose inertia is thus reduced to a point approaching zero before it comes in contact with its back stop set screw 42. The lug 25 acts as a backstop limiting the movement of the auxiliary armature, 9 and the spring member 8 controls the return movement of the auxiliary armature to close the contact springs 14 and 15. It is evident that by adjustiig the position of the lugs 7 and 25 and the backstop 26 which controls the spring member 8 the time of ope-ning or closing the contactl springs 14 and 15 with respect to the movement of the main armature 2 will be advanced or retarded, thus controlling the motive and. driving strokes of the stepping mechanism.

From the description given it is obvious l'lO pole piece of the electroma that there are two distinct magnetic circuits subject to the control of the same electromagnet. Included in one-magnetic circuit is the main armature for drivin the stepping mechanism, and included in t e .other is the'` -auxiliary armature for controlling the cirshunt flux may be controlled by the cross section of the reed 24 connecting it to the The main armature 2, igs. 1 and 2) in moving, swings at 3 on the round-nosed end of the U-shaped piece37. The limit vof the forward movement of the armature 2 is regulated by the position of the set screw 5 and the limit of its backward movement by the position ofthe set screw 4. The air gap (between the armature 2 and the pole piece 11 is regulated by means of the twin screws 29 and the screw 30. To increase the air gap,

the screw 30 is loosened and the-twin screws 29 are tensioned, and conversely to decrease the air gapthetwin screws 29 are loosened and the screw 30 is tensioned. It is obvious that by varying the amount of tension or setup of the twin screws 29 with respect to each other, that the plane of the armature 2 with respect to the plane of the pole piece 11 may be varied. The advantage of this arrangement is that by changing the position of the twin screws 29, the armature 2 may be tilted, if necessary, in order to set it in the general plane of the face of the pole piece 11, thus at all times insuring maximum eiciency between the armature and pole iece. This arrangement obviously allows or the differences which arise commercially in the manufacture of the pole pieces. The pin 31 is slotted as shown at 32 Fig. 5) so as to permit the projection 35 o the fastener 38 (Fig. 4) to engage with the pin 31, locking it in a fixed position. The arm 60 (Fig. 4) is slotted at 36 to permit it to be adjusted to give the. desired tension to the spring 21. When thedesired tension is obtained the bolt 34 is tightened to ret-ain the arm 60 in the desired position. The bolt 34 is tightened by turning it in a clockwise direction, thereby forcing the arm 60 against the fastener 38 which is pivoted at 39. The more the bolt 34 is tightened the more securely the projection 35 is held in position in the slot 32 of the pin 31.

Fig. 6 shows another formof construction of the electromagnet, its armature, and the adjusting mechanism therefor. The core 50 terminates in the pole piece 46. The frame piece 49 which is secured to the core 50 atV 51, and to the frame 53 at 51 and 52, terminates at 41 in around nose pole piece whereon the armature 40 is loose y pivoted. The

frame piece 44 is secured to the frame piece 49 by means of the twin screws 48. The set screw 43 regulates the forwardmovement of the armature 40 and the set screw 42 regulates both the backward movement of the armature 40 and the sizeof the air gap between thev armature 40 and the pole piece 46. In adjusting the mechanism Shown in Fig. 6, the air gap between the pole piece 46 and the main armature 40 may first be determined and thereafter maintained. To permit the main armature 40 to be adjusted 'with respect to the ratchet 56 without varying the air gap between the main armature Yand (pole piece, the pawl 55 is adjustably secure at 57 tothe main armature 40 by means of the twin clamping screwsr 58. By arranging the back sto piece 44 in the manner s own in Fig. 6, it is possible to locate the set screws 42 and 43 member or frame near the pivot 41. This reduces the resulting hammer action produced by the movement of the main armature 40 resulting in less wear upon the moving and movement resisting parts.

It is evident from an examination of Figs. 1, 2 and 6 that the armature 2 (Figs. 1 and 2) and 40 (Fig. 6) function as levers and that the electromagnet, the retractile s ring the pawl controlling the ultimate load), and the pivot or fulcrum of the lever are all yso situated, that all the forces acting u on, and acted on through the medium of tiie lever, operate in parallel planes. It is also evident that the retractile springs 21 (Figs. 1 and 2)' and 54 (Fig. 6) are in juxtaposition to their respective pawls 17 and 55 for-driving the lultimate load, in this case, the rotary ele- 1. In a stepping mechanism, a motor mag-` net, an energizing circuit for said magnet, a main armature, a magnetic reed a magnetic circuit including the reed completely closed when the motor magnet is first energized, means -for controlling 'the movement of the reed to introduce an air gap in the ma circuit aforesaid, a circuit interrupter'in the circuit of the motor magnet, yand means operated by the reed for controlling the circuit interrupter.

2. In a stepping mechanism, a motor magnet, a circuit for energizing the same a main armature, a magnetic reed formin part of a magnetic circuit exclusive of the main armature, `which circuit is entirely close-d when the motor magnet is first enerized, means operated by the main armature or moving the reed to intro-duce one air ga in the magnetic circuit aforesaid, .a circuit interrupter included in the circuit of the motor magnet, and means operated by the reed for opening and closing the circuit interru ter. v

3. a stepping mechanism, an electroetic ` controlled by* the ma and means controlled by the main armature for overcoming the magnetic effect of the electromagnet upon the auxiliary armature. `4:. In a steppingmechanism, a retractile spring, a ratchet, a bearing for said ratchet, means for adjustin the tension 'of the retractile sprin an' a vdevicecontrolled by said spring a justing means for locking the ratchet bearing.

5. In a stepping mechanism, a retractile spring, a ratchet, a bearing for said ratchet, means for adjusting the tension of the retractile spring, a locking device controlled by said spring adjustin means for locking the ratchet bearing, an means for locking said spring adjusting 'means whereby the more securel the last mentioned locking means is tig itened the more securel the ratchet bearing locking device is locke 6. A stepping mechanism comprising a driven member, a bearing for said driven member, a driving member, a spring for operating said driving member and joint means for regulating the spring and securing the bearing.

7. A stepping mechanism -comprising a pole piece, an armature, a round nosed pivot upon which said armature is pivoted, and means for varying the plane of the armature with respect to the plane of the pole piece thereby changin the air gap between said armature and sai pole piece.

8. A stepping mechanism comprising a pole piece, a U shaped framework whereon the armature is pivoted, set screws for varyin thel gap between, and for tilting, the arms o the shaped piece, whereby the air gap between the pole piece and the armature may be varied, and the position of the armature withrespect to the lanel-of the le piece may be changed, andJ means including set screws for limitin the movement of the armature in either direction.

9. A stepping mechanism comprising a pole piece, an armature, a U shaped framework havmg a round nosed ivot whereon the armature is pivoted, a p urality of set screws for varying the space between the arms of the U shaped piece whereby the air gap between the armature and the pole piece may be'varied and, whereby the position of the armature with'respect to the plane of the4 pole. piece may be changed, means for limiting the backward movement of said armature, and means for limiting the forward movement of said armature. l

10. In an electromagnet, a circuit interrupter, a retractile spring, a circuit including the electromagnet and the interrupter, an armature free to move within set limits under control of the electromagnet and the spring, and means for so controllin the opening and closin of the circuit of t e electroma net as to a Sorb or prevent the shock Whic would otherwise occur when the armature reached the limit of its movement.

In witness whereof, I hereunto subscribe my name this 14th day of March, A. D., 1924.

MERLE PEABODY CHAPLIN. 

